package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.constant.SystemConstants;
import com.hmdp.dto.Result;
import com.hmdp.dto.ScrollResult;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Blog;
import com.hmdp.entity.Follow;
import com.hmdp.entity.User;
import com.hmdp.mapper.BlogMapper;
import com.hmdp.service.IBlogService;
import com.hmdp.service.IFollowService;
import com.hmdp.service.IUserService;
import com.hmdp.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import static com.hmdp.constant.RedisConstants.BLOG_LIKED_KEY;
import static com.hmdp.constant.RedisConstants.FEED_KEY;

@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService {
    @Resource
    private IUserService userService;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private IFollowService followService;

    /**
     * 保存博客并推送
     * 实现博客推送 -> 将 key userId, zset blogId 存入内存
     * redis使用zset -> score实现时间戳，以通过时间排序推送
     * @param blog
     * @return
     */
    @Override
    public Result saveBlog(Blog blog){
        UserDTO user = UserHolder.getUser();
        blog.setUserId(user.getId());
        boolean isSuccess = save(blog);
        if(!isSuccess){
            return Result.fail("新增笔记失败!");
        }
        // 查询该用户的粉丝
        List<Follow> follows = followService.query().eq("follow_user_id", user.getId()).list();
        for (Follow follow : follows) {
            Long userId = follow.getUserId();
            String key = FEED_KEY + userId;
            stringRedisTemplate.opsForZSet().add(key, blog.getId().toString(), System.currentTimeMillis());
        }
        return Result.ok(blog.getId());
    }

    /**
     * 点赞/取消点赞 博客
     * redis: key blogId, zset userId
     * 同样，先操作数据库后操作redis
     * @param id
     * @return
     */
    @Override
    public Result likeBlog(Long id){
        Long userId = UserHolder.getUser().getId();
        String key = BLOG_LIKED_KEY + id;
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        if (score == null) {
            // 点赞
            boolean isSuccess = update().setSql("liked = liked + 1").eq("id", id).update();
            if (isSuccess) {
                stringRedisTemplate.opsForZSet().add(key, userId.toString(), System.currentTimeMillis());
            }
        } else {
            // 取消点赞
            boolean isSuccess = update().setSql("liked = liked - 1").eq("id", id).update();
            if (isSuccess) {
                stringRedisTemplate.opsForZSet().remove(key, userId.toString());
            }
        }
        return Result.ok();
    }

    /**
     * 分页查询博客，按点赞数降序排序
     * @param current
     * @return
     */
    @Override
    public Result queryHotBlog(Integer current){
        Page<Blog> page = query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        List<Blog> records = page.getRecords();
        records.forEach(blog -> {
            this.queryBlogUser(blog);
            this.isBlogLiked(blog);
        });
        return Result.ok(records);
    }

    @Override
    public Result queryBlogById(Long id){
        Blog blog = getById(id);
        if (blog == null) {
            return Result.fail("笔记不存在！");
        }
        queryBlogUser(blog);
        isBlogLiked(blog);
        return Result.ok(blog);
    }

    /**
     * 查询前五个点赞的用户
     * @param id
     * @return
     */
    @Override
    public Result queryBlogLikes(Long id){
        String key = BLOG_LIKED_KEY + id;
        Set<String> top5 = stringRedisTemplate.opsForZSet().range(key, 0, 4);
        if (top5 == null || top5.isEmpty()) {
            return Result.ok(Collections.emptyList());
        }
        List<Long> ids = top5.stream().map(Long::valueOf).collect(Collectors.toList());
        String idStr = StrUtil.join(",", ids);
        List<UserDTO> userDTOS = userService.query()
                .in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list()
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());
        return Result.ok(userDTOS);
    }

    /**
     * 查询“收件箱”中博主feed来的博客
     * @param max
     * @param offset
     * @return  ScrollResult
     */
    @Override
    public Result queryBlogOfFollow(Long max, Integer offset){
        Long userId = UserHolder.getUser().getId();
        String key = FEED_KEY + userId;
        //得到指定时间的博客及其时间戳
        //typedTuples按时间戳降序
        Set<ZSetOperations.TypedTuple<String>> typedTuples = stringRedisTemplate.opsForZSet()
                .reverseRangeByScoreWithScores(key, 0, max, offset, 2);
        if (typedTuples == null || typedTuples.isEmpty()) {
            return Result.ok();
        }
        List<Long> ids = new ArrayList<>(typedTuples.size());
        long minTime = 0; // 最小时间戳
        int os = 1; // 时间戳对应的偏移量
        for (ZSetOperations.TypedTuple<String> tuple : typedTuples) {
            // 获取博客id
            ids.add(Long.valueOf(tuple.getValue()));
            // 获取时间戳
            long time = tuple.getScore().longValue();
            if(time == minTime){
                os++;
            }else{
                minTime = time;
                os = 1;
            }
        }

        // 根据id查询blog
        String idStr = StrUtil.join(",", ids);
        List<Blog> blogs = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Blog blog : blogs) {
            queryBlogUser(blog);
            isBlogLiked(blog);
        }

        ScrollResult r = new ScrollResult();
        r.setList(blogs);
        r.setOffset(os);
        r.setMinTime(minTime);
        return Result.ok(r);
    }

    /**
     * 设置blog.name,blog.icon
     * 设置@TableField(exist = false)的属性
     * @param blog
     */
    private void queryBlogUser(Blog blog) {
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    }
    /**
     * 设置blog.isLike
     * //设置@TableField(exist = false)的属性
     * @param blog
     */
    private void isBlogLiked(Blog blog) {
        UserDTO user = UserHolder.getUser();
        if (user == null) {
            // 用户未登录，无需查询是否点赞
            return;
        }
        Long userId = user.getId();
        String key = "blog:liked:" + blog.getId();
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        blog.setIsLike(score != null);
    }
}
